Graphene is a crystal of carbon atoms arranged in a honeycomb lattice. Single and few-layer graphene has emerged as a promising material for novel applications in electronics because the high carrier mobility and perfect charge carrier confinement of graphene result in outstanding electronic transport properties. Graphene thus holds promises for widespread applications including field-effect transistors, super-capacitors, and sensors. The semi-metallic nature of graphene when coupled with high carrier mobility and low opacity also makes graphene a good candidate for use as a transparent conductor for photovoltaic devices, touch panels, and displays. Graphene structures also have high chemical resistance and are relatively flexible when compared to some other transparent conductor materials such as indium tin oxide (ITO). Bilayer graphene (BLG) in particular holds further promise for use in post-silicon electronics applications because a bandgap up to 250 meV can be induced in the material using an electric field, which is not possible with single or monolayer graphene (SLG), and because exciton binding energies in BLG are tunable by electric field-induced bandgap.
A monolayer or single layer graphene is a plane of carbon atoms bonded in a hexagonal array. Multiple layers of graphene are typically formed by first forming a single layer of graphene and them transporting the single layer onto another layer of graphene. The main approach in fabricating graphene has been mechanical exfoliation and chemical vapor deposition (CVD). Growth of large-scale single or few-layers graphene has been shown on Cu or Ni surfaces. For device fabrication, the graphene grown on Cu or Ni is subsequently transferred onto another insulating substrate. In addition to adding complexity, the transportation step increases the risk of contaminating the graphene sheet.
Recently, it has been reported that a laser technique can be used for growing graphene on a nickel foil and also for epitaxially growing graphene on SiC. A method wherein few-layer graphene was grown on a silicon substrate using a laser-based technique without any metal catalysts has also been demonstrated. These methods produce graphene on a conductive substrate, however, and a transfer process is therefore needed for fabricating a graphene device on an insulating substrate.
What is needed therefore is a method of producing single or few layer graphene on a non-conductive surface. A method of producing few-layer graphene without the need to transport a single layer graphene is also needed.